Hirofumi Hirao

Association of anti-human leukocyte antigen and anti-angiotensin II type 1 receptor antibodies with liver allograft fibrosis after immunosuppression withdrawal.

Background Many pediatric patients who receive a living-donor liver transplant undergo withdrawal of immunosuppression (IS). For them, the high incidence of long-term progressive graft fibrosis is of particular concern. Methods We conducted a cross-sectional study including 81 pediatric patients who underwent IS withdrawal after living-donor liver transplant at Kyoto University Hospital and whose serum samples and pathological data could be obtained during the analysis period. We examined the association of donor-specific anti-human leukocyte antigen (HLA) antibody (DSA) and angiotensin II type 1 receptor antibody (anti-AT1R Ab) with posttransplant graft fibrosis. Normalized mean fluorescence intensity (MFI) 5,000 or higher and anti-AT1R Ab concentrations 17 U/mL or higher were both considered high level. The patients were classified into an advanced fibrosis group (AFG) (Ishak score≥3) and a control group (CG) (Ishak score⩽2). Results Only one patient demonstrated DSA class I. Among those who demonstrated DSA class II, more AFG patients than CG patients demonstrated high-level mean fluorescence intensity, although the difference was not significant (64% vs. 39%; P=0.053). The incidence of high-level DSA-DRB1, however, was significantly higher in the AFG than that in the CG (40% vs. 4%; P<0.001), but there was no significant difference in DSA-DQB1 or DSA-DRB345. High-level anti-AT1R Ab was significantly more frequent in the AFG than in the CG (65% vs. 36%; P=0.02). All patients with both high-level DSA-DRB1 and high-level anti-AT1R Ab were found to have advanced fibrosis (P<0.001). Conclusion Anti-AT1R Ab and DSA-DRB1 may be candidates as biomarkers of graft fibrosis; both HLA and non-HLA immunity may be involved in graft fibrosis after IS withdrawal.

Impact of Subnormothermic Machine Perfusion Preservation in Severely Steatotic Rat Livers: A Detailed Assessment in an Isolated Setting

The current drastic shortage of donor organs has led to acceptance of extended‐criteria donors for transplantation, despite higher risk of primary nonfunction. Here, we report the impact of subnormothermic machine perfusion (SMP) preservation on the protection of >50% macrosteatotic livers. Dietary hepatic steatosis was induced in Wistar rats via 2‐day fasting and subsequent 3‐day re‐feeding with a fat‐free, carbohydrate‐rich diet. This protocol induces 50–60% macrovesicular steatosis, which should be discarded when preserved via cold storage (CS). The fatty livers were retrieved and preserved for 4 h using either CS in histidine‐tryptophan‐ketoglutarate or SMP in polysol solution. Graft functional integrity was evaluated via oxygenated ex vivo reperfusion for 2 h at 37°C. SMP resulted in significant reductions in not only parenchymal alanine aminotransferase (p < 0.001), but also mitochondrial glutamate dehydrogenase (p < 0.001) enzyme release. Moreover, portal venous pressure (p = 0.047), tissue adenosine triphosphate (p = 0.001), bile production (p < 0.001), high‐mobility group box protein‐1 (p < 0.001), lipid peroxidation, and tissue glutathione were all significantly improved by SMP. Electron microscopy revealed that SMP alleviated deleterious alterations of sinusoidal microvasculature and hepatocellular mitochondria, both of which are characteristic disadvantages associated with steatosis. SMP could protect 50–60% macrosteatotic livers from preservation/reperfusion injury, and may thus represent a new means for expanding available donor pools.

Intestinal ischemic preconditioning ameliorates hepatic ischemia/reperfusion injury in rats: Role of heme oxygenase 1 in the second window of protection

Preconditioning by brief ischemia protects not only the concerned organ but also other distant organs against subsequent lethal damage; this is called remote ischemic preconditioning (RIPC). This study was designed to investigate the impact of intestinal RIPC on hepatic ischemia/reperfusion injury (IRI) with a special interest in heme oxygenase 1 (HO‐1) induction in the second window of protection (SWOP). Male Wistar rats were randomly assigned to 1 of 2 groups: an RIPC group or a sham group. Before hepatic IRI, either intestinal RIPC, consisting of 2 cycles of 4‐minute superior mesenteric artery clamping separated by 11 minutes of declamping (RIPC group), or a sham procedure (sham group) was performed. After 48 hours of recovery, the rats were exposed to 30 minutes of total hepatic IRI. Transaminase releases and proinflammatory cytokines were determined at several time points after reperfusion. Histopathological analysis and animal survival were also investigated. Intestinal RIPC significantly lowered transaminase release (alanine aminotransferase at 2 hours: 873.3 ± 176.4 IU/L for the RIPC group versus 3378.7 ± 871.1 IU/L for the sham group, P < .001) as well as proinflammatory cytokine production (tumor necrosis factor α at 2 hours: 930 ± 42 versus 387 ± 17 pg/μL, P < .001). The morphological integrity of the liver and the ileum was maintained significantly better with intestinal RIPC; this reached statistical significance not only in Suzukis liver injury score (3.5 ± 0.2 versus 0.7 ± 0.5, P = .007) but also in Parks score for intestinal damage (4.0 ± 0.4 versus 2.0 ± 0.2, P = .007). Animal survival was also markedly improved (83.1% versus 15.4%, P < .001). As a mechanism underlying this protection, HO‐1 was substantially induced in liver tissue, especially in hepatocytes, with remarkable up‐regulation of bradykinin in the portal blood, whereas HO‐1 protein induction in enterocytes was not significant. In conclusion, intestinal RIPC remarkably attenuates hepatic IRI in the SWOP, presumably by HO‐1 induction in hepatocytes. Liver Transpl 21:112‐122, 2015.

Cilostazol attenuates hepatic stellate cell activation and protects mice against carbon tetrachloride-induced liver fibrosis.

Liver fibrosis is a common pathway leading to cirrhosis. Cilostazol, a clinically available oral phosphodiesterase‐3 inhibitor, has been shown to have antifibrotic potential in experimental non‐alcoholic fatty liver disease. However, the detailed mechanisms of the antifibrotic effect and its efficacy in a different experimental model remain elusive.

Thrombomodulin Attenuates Inflammatory Damage Due to Liver Ischemia and Reperfusion Injury in Mice in Toll-Like Receptor 4–Dependent Manner

Liver ischemia reperfusion injury (IRI) is an important problem in liver transplantation. Thrombomodulin (TM), an effective drug for disseminated intravascular coagulation, is also known to exhibit an anti‐inflammatory effect through binding to the high‐mobility group box 1 protein (HMGB‐1) known as a proinflammatory mediator. We examined the effect of recombinant human TM (rTM) on a partial warm hepatic IRI model in wild‐type (WT) and toll‐like receptor 4 (TLR‐4) KO mice focusing on the HMGB‐1/TLR‐4 axis. As in vitro experiments, peritoneal macrophages were stimulated with recombinant HMGB‐1 protein. The rTM showed a protective effect on liver IRI. The rTM diminished the downstream signals of TLR‐4 and also HMGB‐1 expression in liver cells, as well as release of HMGB‐1 from the liver. Interestingly, neither rTM treatment in vivo nor HMGB‐1 treatment in vitro showed any effect on TLR‐4 KO mice. Parallel in vitro studies have confirmed that rTM interfered with the interaction between HMGB‐1 and TLR‐4. Furthermore, the recombinant N‐terminal lectin‐like domain 1 (D1) subunit of TM (rTMD1) also ameliorated liver IRI to the same extent as whole rTM. Not only rTM but also rTMD1 might be a novel and useful medicine for liver transplantation. This is the first report clarifying that rTM ameliorates inflammation such as IRI in a TLR‐4 pathway–dependent manner.

The protective function of galectin‐9 in liver ischemia and reperfusion injury in mice

Galectin‐9 (Gal‐9) has gained attention as a multifaceted player in adaptive and innate immunity. To elucidate the role of Gal‐9, we used a mouse model of partial liver ischemia/reperfusion injury (IRI) with wild type (WT) and Gal‐9 knockout (KO) mice as well as a recombinant galectin‐9 (reGal‐9) protein. We found that the expression of Gal‐9 was enhanced endogenously in the liver especially by hepatocytes and Kupffer cells during warm IRI for a mouse liver, which causes massive destruction of liver tissue. Gal‐9 was released into the extracellular space in the liver and the highest levels in the plasma at 1 hour after reperfusion. The present study elucidates a novel role of Gal‐9 signaling in mouse liver IRI, by using Gal‐9–deficient mice and a stable form of reGal‐9 protein. In the circumstance of Gal‐9 absence, liver damage due to ischemia/reperfusion (IR) exacerbated the severity as compared with WT. On the other hand, exogenously administered reGal‐9 significantly ameliorated hepatocellular damage. It decreased the local infiltration of the inflammatory cells such as T cells, neutrophils, and macrophages, and it reduced the expression of proinflammatory cytokines/chemokines; then, it strongly suppressed the apoptosis of the liver cells. Interestingly, severe liver damage due to IR in Gal‐9 KO mice was improved by the administration of reGal‐9. In conclusion, Gal‐9 engagement ameliorated local inflammation and liver damage induced by IR, and the present study suggests a significant role of Gal‐9 in the maintenance of hepatic homeostasis. In conclusion, targeting Gal‐9 represents a novel approach to protect from inflammation such as liver IRI. Exogenous Gal‐9 treatment will be a new therapeutic strategy against innate immunity‐dominated liver tissue damage. Liver Transpl 21:969‐981, 2015.

Influence of hepatorenal syndrome on outcome of living donor liver transplantation: A single-center experience in 357 patients.

Liver transplantation is the only curative treatment for hepatorenal syndrome (HRS); however, the influence of HRS on the patient and renal outcome after living donor liver transplantation (LDLT) is still unclear. The aim of the present study was to evaluate the influence of HRS on the outcome of LDLT.

Hydrogen Flush After Cold Storage (HyFACS), as a new end‐ischemic ex vivo treatment for liver grafts against ischemia/reperfusion injury

Cold storage (CS) remains the gold standard for organ preservation worldwide, although it is inevitably associated with ischemia/reperfusion injury (IRI). Molecular hydrogen (H2) is well known to have antioxidative properties. However, its unfavorable features, ie, inflammability, low solubility, and high tissue/substance permeability, have hampered its clinical application. To overcome such obstacles, we developed a novel reconditioning method for donor organs named hydrogen flush after cold storage (HyFACS), which is just an end‐ischemic H2 flush directly to donor organs ex vivo, and, herein, we report its therapeutic impact against hepatic IRI. Whole liver grafts were retrieved from Wistar rats. After 24‐hour CS in UW solution, livers were cold‐flushed with H2 solution (1.0 ppm) via the portal vein (PV), the hepatic artery (HA), or both (PV + HA). Functional integrity and morphological damages were then evaluated by 2‐hour oxygenated reperfusion at 37°C. HyFACS significantly lowered portal venous pressure, transaminase, and high mobility group box protein 1 release compared with vehicle‐treated controls (P < 0.01). Hyaluronic acid clearance was significantly higher in the HyFACS‐PV and ‐PV + HA groups when compared with the others (P < 0.01), demonstrating the efficacy of the PV route to maintain the sinusoidal endothelia. In contrast, bile production and lactate dehydrogenase leakage therein were both significantly improved in HyFACS‐HA and ‐PV + HA (P < 0.01), representing the superiority of the arterial route to attenuate biliary damage. Electron microscopy consistently revealed that sinusoidal ultrastructures were well maintained by portal HyFACS, while microvilli in bile canaliculi were well preserved by arterial flush. As an underlying mechanism, HyFACS significantly lowered oxidative damages, thus improving the glutathione/glutathione disulfide ratio in liver tissue. In conclusion, HyFACS significantly protected liver grafts from IRI by ameliorating oxidative damage upon reperfusion in the characteristic manner with its route of administration. Given its safety, simplicity, and cost‐effectiveness, end‐ischemic HyFACS may be a novel pretransplant conditioning for cold‐stored donor organs.

Preventive Effect of Antioxidative Nutrient-Rich Enteral Diet Against Liver Ischemia and Reperfusion Injury

BACKGROUND Liver ischemia and reperfusion injury (IRI) is a major problem associated with liver surgery. This study is aimed to compare the preventive effect of an antioxidative nutrient-rich enteral diet (Ao diet) with an ordinal enteral diet (control diet) against liver IRI. METHODS The Ao diet was an ordinary diet comprising polyphenols (catechin and proanthocyanidin) and enhanced levels of vitamins C and E. Male C57BL/6 mice were fed the Ao or control diet for 7 days before ischemic insult for 60 minutes, followed by reperfusion for 6 hours. The levels of inflammatory cytokines, chemokines, and antioxidant enzymes and oxidative stress were evaluated. RESULTS After 7 days of pretreatment with the Ao diet, the serum levels of vitamins C and E in mice were markedly elevated. The levels of serum aspartate aminotransferase and alanine aminotransferase, as well as the scores of liver necrosis caused by ischemia and reperfusion, were significantly lower in the Ao diet group than in the control diet group. The gene expression levels of inflammatory cytokines and chemokines, such as interleukin-6 and CXCL1, were significantly lower in the Ao diet group. In the liver, the levels of antioxidant enzymes superoxide dismutase 1 (SOD1) and SOD2 were significantly higher and the malondialdehyde levels were significantly lower in the Ao diet group. Cell adhesion molecule expression was significantly lower, and neutrophil and macrophage infiltration was less in the Ao diet group. CONCLUSIONS Antioxidative nutrient supplementation to an ordinary enteral diet may mitigate liver IRI by causing an antioxidant effect and suppressing inflammation.

Myeloid HO-1 modulates macrophage polarization and protects against ischemia-reperfusion injury

Macrophages polarize into heterogeneous proinflammatory M1 and antiinflammatory M2 subtypes. Heme oxygenase 1 (HO-1) protects against inflammatory processes such as ischemia-reperfusion injury (IRI), organ transplantation, and atherosclerosis. To test our hypothesis that HO-1 regulates macrophage polarization and protects against IRI, we generated myeloid-specific HO-1-knockout (mHO-1-KO) and -transgenic (mHO-1-Tg) mice, with deletion or overexpression of HO-1, in various macrophage populations. Bone marrow-derived macrophages (BMDMs) from mHO-1-KO mice, treated with M1-inducing LPS or M2-inducing IL-4, exhibited increased mRNA expression of M1 (CXCL10, IL-1β, MCP1) and decreased expression of M2 (Arg1 and CD163) markers as compared with controls, while BMDMs from mHO-1-Tg mice displayed the opposite. A similar pattern was observed in the hepatic M1/M2 expression profile in a mouse model of liver IRI. mHO-1-KO mice displayed increased hepatocellular damage, serum AST/ALT levels, Suzukis histological score of liver IRI, and neutrophil and macrophage infiltration, while mHO-1-Tg mice exhibited the opposite. In human liver transplant biopsies, subjects with higher HO-1 levels showed lower expression of M1 markers together with decreased hepatocellular damage and improved outcomes. In conclusion, myeloid HO-1 expression modulates macrophage polarization, and protects against liver IRI, at least in part by favoring an M2 phenotype.